An agricultural vehicle known as a harvester “combine” can perform multiple harvesting functions, including picking, threshing, separating and cleaning of grain. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into the combine for further processing. During this processing, grain is separated from crop residue. The crop residue, such as straw, is discharged from the rear of the combine. In many cases, the crop residue is deposited back onto the field in the form of windrows at the back of the combine. The windrows can then be collected by balers or other machinery, after which the collected material can be fed to livestock or used for other purposes.
Windrow material is typically discharged through a chute at the rear of the combine and deposited on the field. The material is often deposited in a generally straight line along the center line of the combine, or in close proximity to the center line. Given the width of the combine, the resulting windrows are spaced relatively far apart from one another. This is not always desirable, because many balers can only collect one windrow per pass when the windrows are spaced far apart.
It is desirable to reduce the velocity of windrow material as it exits the combine. A high discharge velocity can drive the windrow material below the stubble that remains on the field, making collection of the material difficult. Reducing the velocity of the discharged material can create a more fluffy windrow that rests on top of the stubble. For this reason, some combines are provided with relatively long windrow chutes to control the discharge velocity. While longer chutes can reduce discharge velocity of crop residue and create very narrow fluffy windrows, they have the disadvantage of occupying a large amount of space on the rear of the combine, making it difficult to reach the engine access ladder and other areas on the rear of the combine above the chute.
It is also desirable to control the width of the windrow (i.e. the cross dimension of the windrow perpendicular to the direction of movement of the combine). There are instances when wider windrows are desired, and instances when narrower windrows are desired. Wider windrows allow crop residue with a higher moisture content to dry more quickly on the field, because the crop residue is deposited in a thinner layer and spread over more area. On the other hand, if the crop residue is already dry, then a narrower windrow may be more desirable so that the material can be easily picked up with a baler without having to first rake the material into narrower rows. Unfortunately, many conventional windrow chutes lack the ability to adjust the width of windrows because the chutes have fixed geometries.
It is further desirable to control the trajectory of material through the windrow chute as the combine reaches the end of each pass. At the end of each pass, the combine will might execute a 180 degree turn to begin the next pass in the opposite direction. During the turn, crop residue continues to discharge from the windrow chute. The windrow chute may briefly accelerate as the rear end of the combine executes the turn, causing crop residue to exit the chute at a higher velocity, spread out over a wide swath, form an irregularly-shaped path, and/or penetrate below the stubble. These conditions can make it more difficult to collect the crop residue at the end of the windrow.
It is still further desirable to control the position of windrows so that they do not interfere with other equipment during a harvest. For example, it can be desirable to have a tractor and grain cart drive parallel to the combine along the combine's prior travel tracks during a harvest to collect grain from the combine. This process is difficult when windrows are being deposited onto the field along the centerline of the combine. In such cases, the tractor and grain cart must drive over or “straddle” the windrows as they drive alongside the combine. The tractor and/or grain cart may not have adequate ground clearance to straddle the windrows, however. In such a case, the bottom of the tractor and/or grain cart can disrupt the windrows and drag the material. This can make it impractical to collect grain in grain carts during harvesting when windrowing is used.
The foregoing drawbacks and challenges illustrate the need for an improved apparatus and method for depositing crop residue in windrows.